What determines how much your savings will grow
Your savings grow through interest—money the bank pays you for letting them hold your deposit. The amount you earn depends on three things: how much you deposit, the interest rate the bank offers, and how long the money sits in the account. A higher rate means faster growth. A longer time period means more compounding—earning interest on your interest.
Banks set their own rates, so the same $1,000 might earn $5 at one bank and $15 at another. Rates change frequently, sometimes weekly. Online banks typically offer higher rates than brick-and-mortar branches because they have lower overhead costs.
The math is straightforward but the numbers vary widely depending on where you bank. There is no single answer to "how much will my money grow"—it depends entirely on the rate your bank is currently offering and how long you leave the money untouched.
Key Takeaways
- Interest rates on savings accounts vary by bank and change regularly, so you need to check your specific bank's current rate to know what you will earn.
- Online banks usually offer higher rates than traditional banks because they have lower operating costs.
- The longer your money stays in the account, the more you earn from compounding—interest paid on your interest.
- You can use a savings calculator with your bank's current rate to see what a specific deposit will grow to over a specific time period.
How interest rates work in practice
Banks quote interest rates as an Annual Percentage Yield (APY). This is the percentage of your balance you earn per year, including the effect of compounding. If a bank offers 4.50% APY and you deposit $1,000, you will earn roughly $45 in the first year (though the exact amount depends on how often the bank compounds interest—usually daily or monthly).
The rate is not locked in. Banks can raise or lower their rates at any time, and they do this frequently. If you opened an account at 4.50% APY last month and the bank drops to 3.75% next month, your existing balance earns the new rate going forward. You do not lose what you already earned, but future earnings slow down.
Rates also vary by account type. A regular savings account might pay 4.00% APY, while a Money Market account at the same bank might pay 4.50%. High-yield savings accounts (usually online) often pay 4.50% to 5.35% APY, depending on current market conditions.
The difference between straightforward and compound interest
straightforward interest means you earn a percentage on your original deposit only. If you deposit $1,000 at 5% straightforward interest, you earn $50 per year, every year, for a total of $1,050 after one year and $1,100 after two years.
Compound interest means you earn interest on your original deposit plus all the interest you have already earned. After one year at 5% compounded annually, your $1,000 becomes $1,050. In year two, you earn 5% on $1,050, not on $1,000—so you earn $52.50 instead of $50. After two years, you have $1,102.50.
Most savings accounts compound daily or monthly, which means the difference grows faster than annual compounding. The longer the money sits, the more noticeable the difference becomes. Over 10 years, compound interest can add hundreds of dollars compared to straightforward interest on the same deposit and rate.
Real examples at current rates
These examples use rates that were current in early 2024, but your bank's actual rate may be different. Check your bank's website or call them to find your current APY before doing your own math.
| Deposit | Rate (APY) | After 1 Year | After 5 Years | After 10 Years |
|---|---|---|---|---|
| $5,000 | 4.50% | $5,225 | $6,191 | $7,664 |
| $10,000 | 4.50% | $10,450 | $12,382 | $15,329 |
| $5,000 | 2.00% | $5,101 | $5,521 | $6,095 |
The difference between 4.50% and 2.00% is significant over time. On a $10,000 deposit, the higher rate earns you about $2,200 more after 10 years. This is why shopping for a higher-rate account matters, especially if you are planning to leave the money untouched for several years.
Why rates change and what that means for you
Banks adjust their rates based on what the Federal Reserve does with its benchmark interest rate. When the Fed raises rates, banks typically raise what they pay on savings accounts (though usually with a delay). When the Fed cuts rates, banks cut their savings rates too, often quickly.
If you locked in a high rate a few months ago, that rate is yours to keep on your existing balance. But if rates drop, your new deposits will earn less. If rates rise, you might want to move money to a bank offering the new higher rate, though you will not earn back-pay on the money you already have.
This is why it makes sense to check rates every few months if you have a large balance. A 1% difference in APY does not sound like much, but on $50,000 it means $500 per year in lost earnings if you are at a lower-rate bank.
How to find out what your money will actually earn
Your bank statement or online account dashboard shows your current APY. If you cannot find it there, call your bank or check their website—they are required to disclose it clearly.
Once you have the rate, you can use a savings calculator (available free on most bank websites and financial sites) to see what a specific deposit will grow to. Enter your deposit amount, the APY, and the number of years, and the calculator shows you the total with compounding included.
You can also do the math yourself using the compound interest formula, but a calculator is faster and less error-prone. The important thing is knowing your bank's current rate and understanding that it can change.
Frequently Asked Questions
Is the interest I earn on a savings account taxed?
Yes. Interest income is taxable as ordinary income at the federal level and in most states. Your bank will send you a 1099-INT form at tax time if you earned $10 or more in interest during the year. You report this on your tax return. The higher your interest rate, the more tax you may owe on the earnings.
Can I lose money in a savings account?
No. Your principal deposit is protected by FDIC insurance up to $250,000 per depositor per bank. You will not earn much if rates are low, but you will not lose what you put in. The only way to lose money is if you withdraw funds early and the account has a penalty for early withdrawal, which is rare for regular savings accounts.
What is the difference between a savings account and a money market account?
A money market account usually pays a higher interest rate than a regular savings account at the same bank, but may require a larger minimum deposit and limit how many withdrawals you can make per month. Both are FDIC-insured. If you plan to leave the money untouched, a money market account often pays more.
Should I move my money to a higher-rate bank?
If your current bank pays significantly less than other banks (more than 1% difference), moving makes sense for large balances. The process takes a few days. However, if you have a small balance or use other services at your current bank, the hassle may not be worth the extra earnings.
Does compound interest mean my money doubles automatically?
No. Compound interest helps your money grow faster than straightforward interest, but at typical savings rates (2% to 5%), it takes many years for money to double. At 4.50% APY, $1,000 takes roughly 16 years to become $2,000. Compound interest is powerful over decades, not months.